الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Weirs and canal faIls are commonly used to control both discharges and water levels
in irrigation and drainage channels. Canals cross sections are designed considering a
uniform flow condition. Construction of weirs and falls, in open channels, violates the
flow uniformity in such channel either by creating a backwater or a drawdown profile
of water surface upstream such structures. The CUITent method used in the design of
weirs and falls dimensions can not satisfy the flow uniformity in open channels.
In the current problem a new technique is presented to create a uniform flow
condition using a weir of a trapezoidal opening. The problem was studied analytically
and experimentaIly. In the analytical study, different types of weir opening were
tested such as; rectangular, triangular, and trapezoidal shape of weir opening.
The Root Mean Square Error (RMSE), for the difference between canal and weir
discharges, was computed, then a solver tool in Microsoft excel® was used to
minimize the value of RMSE. The trapezoidal shape of weir opening was the only
type that satisfies the flow uniformity.
The experimental study was carried out to investigate the effect of the main
parameters on the discharge coefficient of the trapezoidal weir such as; crest length
and crest height of weir, in addition to the slope of trapezoidal sides. Different models
for the trapezoidal shape of weir opening were used in the experimental setup
prepared for this purpose.
Analysis of results indicated that the discharge coefficient Cd decreased with the
increase of the crest length of the weir (b), height of weir(PwJ, and the angle of weir
(B).
Results of the study were presented in both graphical and tabulated forms.